33 
iiio' too deep. They pot nearly all the stem into the ground; this gives 
easy access to the Cnt-worin to destroy tlie heart of the cabbage; they 
wonld do much better not to plant so dee]>, especially the late-grown 
kinds, as the hard stem is less liable to be cnt than the heart of the 
c>abbage. 
JuJij 31, 1885. — In yonr favor of the 17th instant you requested me to 
continne my experiments as heretofore with infusions of Tansy, Ailan- 
thns, stramonium. Mandrake root, Elder, and tomato leaves, in order 
to give a definite answer as to which may be of value as an insecticide 
and which are worthless. I beg leave to say I have gone to work very 
willingly to try to answer this important question, and made tests on 
various insects. 
As most of the above plants are now easily procured, I made infusions 
in large quantities, but of about the same strength as heretofore. I find 
it is better to let these leaves dry two or three days before the infusions 
are made. These liquids seem also to gain strength by age. At a week 
or ten days old they are much stronger than when first made. One 
l)ound weight of the partially dried leaves to one gallon of water makes 
a good wash. I first tried the relative value of these infusions on some 
brown and yellow hairy caterpillars, the larvae of a Bomb^^cid moth 
(Arctia virginica), li- to 2 inches long, which had been very plenty in 
this locality, on the Sunflower. I marked a certain number of plants for 
each test, and sprayed and wetted both sides of each leaf thoroughly. 
They all continued to eat the leaves after this as before; but with those 
sprayed with ailanthus, stramonium, and mandrake not nearly so raven- 
ously — they seemed rather dainty in their biting. 
Next day I wetted again as before, with about the same result; but 
when 1 wetted the worms thoroughly with stramonium they fell off and 
crawled away, and seemed not to ascend the plant any more. 
Then, in order to satisfy myself as to the merits of the different liquids, 
I collected a number of these caterpillars and i)laced them in six groups, 
on a short piece of board. I wetted them all over equally. They were 
all able to crawl out of their bath; but, when I i)ushed them back and 
wetted their heads, they did not get out again from either mandrake, 
ailanthus, or stramonium. The others crawled out of several wettings ; 
but these remained on the board, and were dead next day. 
About the middle of the month I sowed a patch of white turnips in 
drills, for the purpose of testing these liquids on the Turnip Fly {Raltica). 
They were up in about four days. I commenced wetting them; not all, 
but part of each of six rows. I found it was necessary to wet them every 
day for a week, and afterwards two or three times, before they got 
ahead, in order to keep down this pest ; and where I did not wet them 
they were all eaten off" in about seven or eight days, and I could not 
say positively which of these liquids was the best. 
I tried these infusions also on the Grai^e-vine Thrips, on an outdoor 
arbor, and both sides of the leaves had to be wetted. In this case the 
02(38— Bull. 11 3 
